Food preparation appliance

ABSTRACT

An apparatus for heating food includes a base and a lid coupled to one another by a hinged handle. Two fluid-filled thermal fluid vessels with flexible surfaces are installed in the lid and base to form a chamber for holding a food item in a low temperature cooking container f. The thermal fluid vessels may be replaced with high temperature cooking plates to sear or brown the food items. A user of the appliance is protected from exposure to hot thermal fluid retained in the vessels during low temperature cooking.

FIELD OF THE INVENTION

Embodiments of the invention are related generally to equipment forelectric appliances for preparing food by heating and/or cooling thefood.

BACKGROUND

Low temperature precision cooking is the practice of cooking food forextended periods in high thermal conductivity environments at aprecisely controlled temperature. Sous vide is an example of lowtemperature precision cooking, where low temperature cooking may referto cooking at temperatures below the boiling point of water. The sousvide method places a food item to be cooked in a watertight and possiblyairtight container that is sealed and submerged in a water bath held ata constant selected temperature, preferably controlled to within 0.1degree Celsius of a selected cooking temperature. Sous vide cooking maypreserve food flavor and nutritional value better than high-temperaturecooking methods.

It may be difficult to control the water bath to remain constant withina relatively narrow temperature range. Furthermore, there may be asafety risk for persons working in the vicinity of the heated waterbath, who may inadvertently come into contact with the hot water. Aftera food item has reached the desired cooking temperature and is cookedsufficiently for safe consumption, it may still be preferable to brownthe food to enhance the flavor and surface texture and improve thevisual appeal of the food.

SUMMARY

An apparatus for heating a food item includes a low temperature cookingcontainer formed from two of a thermal fluid vessel. An example of athermal fluid vessel includes a heat transfer plate and a flexible panelattached to the heat transfer plate with a watertight fluid chamberformed between the flexible panel and the heat transfer plate.

The apparatus further includes a base configured for removableattachment of a first of the thermal fluid vessel; and a lid movablycoupled to the base, the lid configured for removable attachment of asecond of the thermal fluid vessel. The first and second thermal fluidvessels, when pressed together by closing the lid against the base, forma sealed chamber in a low temperature cooking container for cooking thefood. Separating the lid from the base separates the first thermal fluidvessel from the second thermal fluid vessel, thereby opening the lowtemperature cooking container.

The apparatus may further include a first and a second high temperaturecooking plate, wherein the first high temperature cooking plate isconfigured for removable attachment to the base after removal of thefirst thermal fluid vessel, and the second high temperature cookingplate is configured for removable attachment to the lid after removal ofthe second thermal fluid vessel. At least one of the first and secondhigh temperature cooking plates includes an integrally formed heatingelement configured for high temperature cooking. The base may optionallyinclude a heating element positioned for heating the first hightemperature cooking plate. The lid may optionally include a heatingelement positioned for heating the second high temperature cooking plate

A container heating element may optionally be formed as an integral partof the flexible panel in at least one of the first and second thermalfluid vessels. The container heating element may alternatively bepositioned inside the fluid chamber or attached to a surface of theflexible panel.

The apparatus may further include a controller electrically connected tothe container heating elements in the first and second thermal fluidvessels. A temperature sensor may optionally be electrically connectedto the controller, wherein the temperature sensor is positioned tomeasure a temperature on the high temperature cooking plate. A secondtemperature sensor may optionally be electrically connected to thecontroller, wherein the second temperature sensor may be positioned onthe low temperature cooking container to measure a temperature insidethe fluid chamber.

The apparatus may optionally include a motor electrically connected tothe controller and an agitator configured to be rotated by the motor,wherein the agitator is rotatably coupled to the heat transfer plate inat least one of the first and second thermal fluid vessels, and theagitator positioned to stir a fluid in the fluid chamber.

The controller may be configured to detect a presence of the hightemperature cooking plate and the thermal fluid vessel in the base andlid and control the base heating element, the lid heating element, andthe container heating element in response to a detected result.

A food chamber for receiving the food to be heated is formed between thefirst thermal fluid vessel and the second thermal fluid vessel when thelid is lowered onto the base. A watertight seal is formed between thefirst thermal fluid vessel and the second thermal fluid vessel by agasket surrounding a food contact surface on each vessel. The gaskets onthe first and second thermal fluid vessels may optionally be configuredto allow air to escape from the food chamber when the lid is loweredonto the base.

An example apparatus may optionally include a vacuum pump in fluidcommunication with the food chamber, wherein the flexible panel on thefirst thermal fluid vessel is drawn toward the flexible panel on thesecond thermal fluid vessel by operation of the vacuum pump.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a pictorial view toward the top and side of an example of afood preparation appliance with the lid moved away from the base byoperation of a hinged handle to show examples of a food contact surfaceon a thermal fluid vessel removably attached to the base, with a secondthermal fluid vessel removably attached to the lid.

FIG. 2 shows the example appliance of FIG. 1 with the lid presseddownward onto the base, thereby forming a low temperature cookingcontainer by pressing the thermal fluid vessel in the base against thethermal fluid vessel in the lid to form a food chamber between thevessels.

FIG. 3 is a front view of the example of an appliance from FIGS. 1-2 .

FIG. 4 is a side view of the example of an appliance from FIGS. 1-3 .

FIG. 5 is a pictorial view of the base and lid of the previous figures,with the lid raised away from the base and a heating element in the baseexposed by removal of the thermal fluid vessel.

FIG. 6 is a view toward the top surface of the lid of the appliance,showing positions of cross-sectional views in other figures.

FIG. 7 is a cross-sectional view A-A of the appliance closed as in FIG.4 . A position and viewing direction for the cross section is marked bya section line A-A in FIG. 6 .

FIG. 8 is a pictorial view of an example of a food contact surface on aflexible panel attached to the rigid side walls of a heat transfer platefrom a thermal fluid vessel.

FIG. 9 is a view toward the food contact surface of the example thermalfluid vessel of FIG. 8 .

FIG. 10 is a view toward the front side of the example thermal fluidvessel of FIGS. 8-9 .

FIG. 11 is a side view of the example thermal fluid vessel of FIGS. 8-10.

FIG. 12 shows a pictorial view of an example of a low temperaturecooking container formed from an upper thermal fluid vessel in contactwith a lower thermal fluid vessel.

FIG. 13 is a view toward a top side of the example low temperaturecooking container of FIG. 12 .

FIG. 14 is a cross-sectional view B-B of an upper thermal fluid vesseland a lower thermal fluid vessel separated by a void space correspondingto a food chamber for receiving a food item to be heated. A location andviewing direction for the cross-sectional view is marked by a sectionline B-B in FIG. 13 .

FIG. 15 is a cross-sectional view C-C of the example appliance of theprevious figures, showing examples of two high temperature cookingplates replacing the two thermal fluid containers of the previousfigures.

FIG. 16 shows a view toward a food contact surface formed with optionalchannels on an example high temperature cooking plate.

FIG. 17 is a side view of the example high temperature cooking plate ofFIG. 16 , showing an example of a latch mechanism for retaining the hightemperature cooking plate and the thermal fluid vessel in the base.

FIG. 18 is a block diagram showing examples of electrical components andelectrical connections in some embodiments of the cooking appliance.

DESCRIPTION

A cooking appliance provides for cooking of a food item by exposing thefood to a pair of opposing food contact surfaces heated to a relativelylow temperature by contact with a thermal transfer fluid such as wateror oil. The thermal transfer fluid is retained in a liquid-tight thermalfluid vessel and is heated by a heating element that maintains thetemperature of the fluid, the food contact surfaces, and therefore thefood item, within a narrow range of a selected cooking temperature. Thefood to be cooked is held in a food chamber between two thermal fluidvessels pressed against one another to form a low temperature cookingcontainer, one thermal fluid vessel removably retained in the lid of theappliance and one in the base. The thermal fluid vessels seal to oneanother when the lid is closed onto the base. When the food item hasbeen cooked to a selected degree of doneness, the food item may removedfrom the low temperature cooking container formed by the two thermalfluid vessels by raising the lid from the base to open the food chamberbetween the vessels. The two thermal fluid vessels forming the lowtemperature cooking container may be replaced by a pair of hightemperature cooking plates which may be heated sufficiently to sear orbrown the food item.

Low temperature cooking to preserve flavor and nutritional value, andhigh temperature cooking to provide preferred texture and visualappearance of a food item, may therefore be achieved with a singleappliance. Furthermore, because the thermal transfer fluid is containedwithin a sealed container, a person using the appliance is not exposedto hot fluid while placing food in the container or removing cooked foodfrom the container. Embodiments of the disclosed cooking applianceprovide the advantages of sous vide cooking without exposing nearbypersons to burns from hot immersion baths, in contrast to traditionalsous vide equipment.

FIGS. 1-5 show views of an example cooking appliance embodiment 100configured for low temperature cooking. A lower housing 102, alsoreferred to as a base 102, is movably coupled to an upper housing or lid101, for example by a handle 706, although other methods for couplingthe lid and base will be known to a person of ordinary skill in the art.The handle may be rotatably coupled to the base and lid by hinges 103.The lid and base are preferably coupled to one another in a manner thatpermits objects of different thicknesses to be placed between the lidand base, for example food items, a high temperature cooking plate, anda low temperature container. A thermal fluid vessel 702 installed in thelid may be pressed against another thermal fluid vessel 704 in the baseby lowering the lid toward the base, as suggested in the example of FIG.2 . A gasket 110 on each of the upper and lower thermal fluid vesselsseals a food item to be cooked into a space between the containers. Thegaskets are shaped to allow air to be expelled from the space betweenthe vessels when the lid is closed, forming a liquid-tight seal aroundthe food item during low temperature cooking. An upper heat transferplate 104 forms part of the upper thermal fluid vessel 702 in the lid. Alower heat transfer plate 105 forms part of the lower thermal fluidvessel 704 in the base. The heat transfer plates distribute thermalenergy evenly and efficiently to a thermal fluid retained in a fluidchamber in thermal fluid vessel. A latch release 710 in the base andanother latch release 710 in the lid may be operated to remove thethermal fluid vessels from the appliance, either for cleaning or toinstall high temperature cooking plates.

FIGS. 3-4 show example views of the closed appliance, with the upperthermal fluid vessel 702 and the lower thermal fluid vessel 704 incontact with one another and sealed to one another by a pair of opposinggaskets 110 that surround the food chamber formed between the thermalfluid vessels (702, 704). Electrical connections between the base andlid may be made through a flexible multiconductor cable 708.

The base and lid each contain a heating element as suggested in theexample of FIG. 5 . The heating elements (106, 107) are visible in theexample of FIG. 5 because the removable upper and lower thermal vessels(702, 704) and upper and lower high temperature cooking plates 742 havebeen removed from the appliance 100. The heating element 107 in the baseand the heating element 106 in the lid may be controlled for both hightemperature cooking and low temperature cooking.

Cross-sectional view A-A in FIG. 7 from the example apparatus 100 ofFIG. 6 shows examples of some internal details of an applianceembodiment 100. The appliance 100 is shown configured for lowtemperature cooking, with an upper thermal fluid vessel 702 removablyretained in the lid 101 and a lower thermal fluid vessel 704 removablyretained in the base 102. The upper and lower thermal fluid vessels areexamples of two parts of a movable thermal fluid-filled flexiblecontainer 108. Components installed in the base include a lower heatingelement 107 positioned to contact the lower heat transfer plate 105 inthe thermal fluid vessel or the high temperature cooking plate 742 (ref.FIG. 15 ). The lower heating element 107 may alternatively be formed asan integral part of the high temperature cooking plate.

A liquid-tight electrical connector having a fixed part 724 and aremovable part 722 provides an electrical connection from an electroniccontroller 112 (ref. FIG. 18 ) in the base 102 to a thermal fluidtemperature sensor 606 positioned to measure a temperature of a thermalfluid in the fluid chamber 109 of the thermal fluid vessel (702, 704).In some embodiments of an appliance 100, an optional electric motor 303in the base is detachably coupled to an agitator 302 in the fluidchamber 109 through a liquid-tight seal and drive coupling 748. In otherembodiments, the motor and agitator may be coupled to one anothermagnetically or inductively without a direct mechanical connection. Inyet other embodiments, the motor and agitator may be omitted. A heatingelement 107 may be installed in the base or may alternatively beprovided as an integral part of a heat transfer plate 105. A thermalfluid fill cap 716 provides for filling and removing thermal fluid suchas oil or water from the fluid chamber 109 in the thermal fluid vesselon the base.

In the lid 101, another temperature sensor 604 may be positioned to reada temperature of a food item being prepared. Electrical connectionsbetween the controller 112 and the sensor 604 may be made throughanother liquid-tight electrical connector (722, 724). A heating element106 may be installed in the lid or may alternatively be provided as anintegral part of a heat transfer plate 104. A thermal fluid fill cap 716provides for filling and removing thermal fluid such as oil or waterfrom the fluid chamber 109 in the low temperature cooking container inthe lid.

In the example of FIG. 7 , a food item to be cooked would be placedbetween the flexible panel 736 of thermal fluid vessel in the base andthe corresponding flexible panel in the thermal fluid vessel in the lid,the space between the flexible panels 736 corresponding to a foodchamber 718 (ref. FIG. 14 ). Liquid that accumulates in the food chambermay be withdrawn through tubing 730 coupled to a drip receptacle 726with a cover 728. Liquid may be withdrawn by a vacuum pump 624 installedin the base or alternatively in the cover, or an external vacuum pumpmay be connected to the drip receptacle. Gaskets 110, one on each of theupper and lower thermal fluid vessels, contact one another to form aliquid-tight seal around the food chamber between the vessels. Thegaskets are configured to allow air to escape from the food chamber whenthe lid is closed onto the base, forming a liquid-tight seal when thelid is closed. A food item being cooked in the food chamber 718 may beremoved from the chamber by raising the lid away from the base,unsealing the gaskets 110 from one another and exposing the food item toview.

Examples of a low temperature cooking container 108 comprising twothermal fluid vessels, an upper vessel 702 and a lower vessel 704, areshown in FIGS. 9-14 . Rigid side walls 740 are attached to, oralternatively formed as an integral part of, a heat transfer plate (104,105). The heat transfer plate and side walls may be made from metal withgood thermal conductivity, e.g. aluminum, steel, stainless steel, and soon. A flexible panel 736 is sealed to the side walls to form a fluidchamber 109 inside the container. The flexible panel may be made fromsilicone rubber or another flexible, food-safe material capable ofsustained exposure to hot thermal fluid, salt, oil, water, grease fromfood, and so on. The exposed surface of the flexible panel 736 providesa food contact surface 732, against which a food item is placed duringcooking. Channels 738 may optionally be formed in the food contactsurface 744 to permit liquid to drain away from a food item beingcooked. An area for locating food 734 may be formed to be more flexiblethan other parts of the flexible panel to permit the area 734 to conformmore readily to the surface of the food item in the food chamber 718.The gasket 110 surrounds the outer edges of the flexible panel 736.

Some details of an example low temperature cooking container 700including a food chamber 718, upper thermal fluid vessel 702, and lowerthermal fluid vessel 704 are shown in a cross-sectional view in FIG. 14. Container walls 501A are joined to, or alternatively formed as anintegral part of, a thermal transfer plate (104, 105), with a fluidchamber 109 formed between the flexible panel 736 and the thermaltransfer plate. A container heating element 720 may be formed as anintegral part of the flexible panel or may alternatively be positionedinside the fluid chamber 109. A space between the flexible panels 736,surrounded by the gaskets 110 on each container, forms the food chamber718 for holding a food item to be cooked. In embodiments having anoptional vacuum pump, the flexible panels may be drawn toward oneanother, into closer contact with a food item being pumped, by partiallyevacuating the food chamber 718.

FIG. 15 shows an example of the appliance embodiment 100 configured forhigh temperature cooking, for example searing or browning of a fooditem. In the example of FIG. 15 , the low temperature cooking container108 has been removed from the appliance 100 and replaced by an upperhigh temperature cooking plate 742 and a lower high temperature cookingplate 742. The opposing food contact surfaces 744 on each plate 742define the food chamber 718. When a food item is placed on the lowerplate in the food chamber 718, the lid may be lowered to place the upperplate in contact with the food to permit both sides of the food to begrilled, browned, or seared simultaneously. As suggested in the exampleof FIG. 16 , the high temperature cooking plates 742 may be formed withchannels 746 to permit liquid to drain away from the food and to form apattern of grill marks on the food. Some embodiments of a hightemperature cooking plate 742 omit the channels 746, having instead aflat top surface useful as a griddle.

FIG. 17 shows an example of a latch arm positioned to capture and retainthe high temperature cooking plate 742 or thermal fluid vessel (702,704) in the base. A second latch arm is positioned on an opposite sideof the base. A similar arrangement of latch arms is provided in the lid.Each latch arm is activated by pressing against a latch release 710 onthe exterior of the base and lid. The latch arm captures a ridge 712formed along an outer wall of the heat transfer plate (104, 105) andalong an outer edge of the high temperature cooking plate 742.

The upper and lower high temperature cooking plates 742 and upper 702and lower 704 thermal fluid vessels may alternatively be removablycoupled to the lid and base by spring clips, clamps, captive bolts, andother means for removable mechanical connection.

Examples of electrical components and electrical connections in anappliance embodiment 100 are shown in a block diagram in FIG. 18 . Anelectronic controller 112 includes a processor 632 implemented inhardware, for example a microprocessor or microcontroller, and memorydevices 634 in data communication with the processor. Some of the memory634 may be nonvolatile memory that retains information when electricalpower is removed. Components which send electrical signals to theprocessor include a lid closure detector 600, a heat transfer plate typedetector 602, a plate temperature sensor 604, and a thermal fluidtemperature sensor 606. One or more status displays and/or indicatorsprovide a user of the appliance with information about cooking optionsavailable for a detected heat transfer plate type 608, a temperaturedisplay 610, for example a desired set point temperature or a measuredtemperature of a food item being cooked, and a status indicator 612 forthe cooking process, for example a cooking time setting, an errorcondition such as no heat transfer plate detected or no thermal fluiddetected in the fluid chamber, an amount of cooking time remaining, ahot surface indicator, and so on.

Control inputs may be provided to permit a user of the appliance toselected time and temperature parameters, for example a set pointtemperature for cooking 614, a cooking time duration at the set pointtemperature 616, and a searing preference 618, i.e., the degree ofsearing desired. Other user-selectable parameters that may be sent tothe processor 632 include the type of food being cooked 620, e.g. beef,chicken, vegetables, and so on, and a degree of doneness 622 desired forthe food item, for example rare, medium, well done, and so on.

The controller 112 may direct operation of a vacuum pump 624, anagitator 626, and heating elements 628 in the lid, base, low temperaturecooking containers, heating elements 630 in the high temperature cookingplates, in response to detection of lid closure 600, detection of thetype of heat transfer plate present (e.g., low temperature cookingcontainer or high temperature cooking plate), user input parameters, andsystem status and/or error conditions.

Unless expressly stated otherwise herein, ordinary terms have theircorresponding ordinary meanings within the respective contexts of theirpresentations, and ordinary terms of art have their correspondingregular meanings.

The invention claimed is:
 1. An apparatus, comprising: a thermal fluidvessel, comprising: a heat transfer plate; and a flexible panel attachedto said heat transfer plate with a fluid chamber formed between saidflexible panel and said heat transfer plate; a base configured forremovable attachment of a first of said thermal fluid vessel; a lidmovably coupled to said base, said lid configured for removableattachment of a second of said thermal fluid vessel; a controllerelectrically connected to a heating element in said base; an electricmotor electrically connected to said controller; and an agitatorconnected to said motor by a drive coupling and rotatably coupled tosaid heat transfer plate in at least one of said thermal fluid vessels,said agitator positioned to stir a fluid in said fluid chamber.
 2. Theapparatus of claim 1, wherein said first and second thermal fluidvessels form a low temperature cooking container with a sealed chamberfor cooking a food item when said lid is closed against said base. 3.The apparatus of claim 1, wherein separating said lid from said baseseparates said first thermal fluid vessel from said second thermal fluidvessel.
 4. The apparatus of claim 1, further comprising a first hightemperature cooking plate and a second high temperature cooking plate,wherein said first high temperature cooking plate is configured forremovable attachment to said base after removal of said first thermalfluid vessel, and said second high temperature cooking plate isconfigured for removable attachment to said lid after removal of saidsecond thermal fluid vessel.
 5. The apparatus of claim 4, wherein atleast one of said first high temperature cooking plate and said secondhigh temperature cooking plates includes an integrally formed heatingelement configured for high temperature cooking.
 6. The apparatus ofclaim 4, wherein said base further includes a heating element positionedfor heating said first high temperature cooking plate.
 7. The apparatusof claim 4, wherein said lid further comprises a heating elementpositioned for heating said second high temperature cooking plate. 8.The apparatus of claim 1, wherein at least one of said first and secondthermal fluid vessels further comprise a container heating elementformed as an integral part of said flexible panel.
 9. The apparatus ofclaim 1, wherein at least one of said first and second thermal fluidvessels further comprise a container heating element positioned insidesaid fluid chamber.
 10. The apparatus of claim 1, wherein at least oneof said first and second thermal fluid vessels further comprise acontainer heating element attached to a surface of said flexible panel.11. The apparatus of claim 1, further comprising a temperature sensorelectrically connected to said controller, said temperature sensorpositioned to measure a temperature on said high temperature cookingplate.
 12. The apparatus of claim 1, further comprising a secondtemperature sensor electrically connected to said controller, saidsecond temperature sensor positioned on one of said thermal fluidvessels to measure a temperature inside said fluid chamber.
 13. Theapparatus of claim 1, wherein said controller is configured to detect apresence of a high temperature cooking plate and said thermal fluidvessel and control said heating element in response to a detectedresult.
 14. The apparatus of claim 1, further comprising: a first latchcoupled to said base, said first latch positioned to retain said firstthermal fluid vessel; and a second latch coupled to said lid, saidsecond latch positioned to retain said second thermal fluid vessel. 15.The apparatus of claim 1, wherein a food chamber for receiving a fooditem to be heated is formed between said first thermal fluid vessel andsaid second thermal fluid vessel when said lid is lowered onto saidbase.
 16. The apparatus of claim 15, wherein a watertight seal is formedbetween said first thermal fluid vessel and said second thermal fluidvessel by a gasket surrounding a food contact surface on each of saidthermal fluid vessels.
 17. The apparatus of claim 16, wherein saidgaskets on said first and second thermal fluid vessels are configured toallow air to escape from said food chamber when said lid is lowered ontosaid base.
 18. The apparatus of claim 15, further comprising a vacuumpump in fluid communication with said food chamber, wherein saidflexible panel on said first thermal fluid vessel is drawn toward saidflexible panel on said second thermal fluid vessel by operation of saidvacuum pump.